Coronal cementum in the horse molar teeth.

Abstract

We examined the morphology of the horse coronal cementum, to study Sharpey's fibers and the blood vessels which become covered with coronal cementum. Histological studies were carried out on 12 functioning mandibular molar teeth of horses, immediately after slaughter. The arrangement of fundamental microstructures composed of collagen fibers (Sharpey's fibers) in coronal cementum and the distribution of blood vessels were studied by light and scanning electron microscopy, and light microscopy was used to observe the shape and distribution of the cemento -enamel junction. The molars were hypsodont, with long crowns and short roots. The apices were open as a result of continuous growth. Pericoronal cementum had a laminated structure, which may have been formed intermittently by cementoblasts in the periodontal ligament and at the eruption in the gingiva. The diameter of Sharpey's fibers at their insertion into cementum was about 50μm. These fibers had diameters of 20-25μm in the deep layer and in the surrounding mineralized cementum. The vascular system was well developed in the concave portion on the buccal and lingual surfaces of the crown. Along the cemento-enamel junction relatively large blood vessels had entered the concave region, and along their way they gave off numerous branches in the coronal cementum. There were sinusoidlike vessels on a part of the enamel surface. The cemento-enamel junction in the horse crown had a characteristic structure: the enamel surface had a number of scallop-shaped resorption concavities, which provided firm connection between the cementum and the enamel.